The present invention relates to a method and an apparatus for the shaping of plastics material pre-forms into plastics material containers. Machines of this type, referred to below as blow-moulding machines, have long been known from the prior art. It is usual in this case for plastics material pre-forms to be transferred to a blow-moulding station and for this blow-moulding station to be arranged on a movable carrier, for example a rotatable blow-moulding wheel. During the conveying of the plastics material pre-form situated inside the blow-moulding station it is blown or expanded by being acted upon with compressed air in order to form a plastics material container. For this purpose the plastics material pre-form is acted upon at very high pressure, for example over 40 bar.
It is also known from the prior art for blow moulds of this type or the carriers thereof to be locked with one another during the expansion process. After the actual expansion, the pressure inside the container is reduced again and the container is released. In this case, it should be noted that at a specific point on the blow-moulding station along its conveying path, it has to be released again so that it can be opened again without damage.
In this case, it is usual in the prior art for the release of the container to be initiated at a process angle or at a pre-set process time, so that the container is completely released in every case at the aforesaid point in time, so that the blow-moulding station can be opened in this way without risk. Accordingly, the starting time at which the release of the plastics material pre-form is started is set relatively early in order to ensure that the pressure is released sufficiently at the aforesaid point in time.
In many cases, however, this leads to a waste of process time, since it would frequently be desirable to maintain this process time or the pressure inside the containers as long as possible.